b - Centrum Textil

b - Centrum

NEW WAY OF MEASUREMENT AND CALCULATION FLEXURAL RIGIDITY OF YARN AND FIBRE Ludmila Fridrichová 1 , Josef Mevald 2 , Iva Mertová 3 1 TECHNICAL UNIVERSITY OF LIBEREC, Faculty of textile engineering, Halkova 6, Liberec, Czech Republic , ludmila.fridrichova@vslib.cz 2 TECHNICAL UNIVERSITY OF LIBEREC, Faculty of mechanical engineering, Halkova 6, Liberec, Czech Republic, josef.mevald@vslib.cz 3 TECHNICAL UNIVERSITY OF LIBEREC, Faculty of textile engineering, Halkova 6, Liberec, Czech Republic , iva.mertova@vslib.cz 1. INTRODUCTION Are values, which it is possible in fibres or in yarn relatively easily scale, for example fineness, strength, elongation, number twists of yarn. We hasn't problems in fibres determine cross – section of fibre, longitude etc. Exist however characteristics, at which it is impossible so uniquely determine their values. Between these characteristics belongs to flexural stiffness how fibres so yarn. This paper presents just those characteristics measurement and calculation flexural rigidity. Shows new way for measurement and calculation flexural stiffness yarn and fibre. Flexural rigidity fibre he's got to the front especially at the moment of, when started create computer designs clothes. It was necessary, so as to cloth designed by computer was drape as well as is draped real dress. Is know, that is drape very influenced by flexural stiffness of material. Therefore started research take in this direction, i. e. research of flexural behaviour fabrics, yarns and fibres. Are many studies, which shows, how is measured and calculated flexural stiffness fabrics, however less studies think out problems flexural stiffness knitting, yarns and fibres. Authors of paper [1] describe measurement of flexural rigidity of fibre. They measured flexural stiffness of fibre with device – micro bending measurement, which was operated under microscope. At the close of paper, authors submit, that data scattering is relatively large. To computation of flexural stiffness authors use values I - moment of inertia of area. Because was investigated flexural stiffness woollen fibre, wasn't problem determine value I. Cross – section of fibre is circular so I=πd 4 /64. Calculation moment of inertia of area for cross - section of cotton fibre would be very complicated. New way to measure flexural stiffness of fibre or yarn can be method described with the following parts of this paper. Input value for calculation flexural stiffness isn't cross - section of fibre but fineness, angle and longitude overhanging of sample. 2. PRINCIPLE OF NEW WAY Method measurement coming - out from procedure, which was applied above all on fabrics and was already published e.g. in reports [2], [3]. Principle is simple. Fabric fix on some end, second end will stay free, next we digitalize picture of inflexed sample. We use program MathCad for